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Geron Announces Publication of Data on GRN163, a Telomerase Inhibitor, in Animal Models of Human Brain Tumors


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Posted on: 07/01/2004

Geron Announces Publication of Data on GRN163, a Telomerase Inhibitor, in Animal Models of Human Brain Tumors

July 01, 2004 07:30 AM US Eastern Timezone

MENLO PARK, Calif.--(BUSINESS WIRE)--July 1, 2004--Geron Corporation (Nasdaq:GERN) announced today the publication of preclinical testing of GRN163, its first-generation telomerase inhibitor drug, in models of human glioblastoma, one of the deadliest forms of brain cancer. The results indicate that GRN163 can prevent or suppress the growth of human glioblastoma tumor cells in mice and rats. In addition, the data suggest that intracranial injection of GRN163 achieves robust distribution of the compound in the brain. The paper, authored by scientists at Geron and the Brain Tumor Research Center and Department of Pathology, University of California, San Francisco, appears in the July 2004 issue of the journal Neuro-Oncology and is available online at http://neuro-oncology.mc.duke.edu.

In three independent studies of athymic (immune-compromised) mice, human malignant glioblastoma cells were implanted under the skin of the flank, and allowed to grow to various sizes. The resulting tumors were then treated with injections of GRN163 plus a lipid carrier. In each study, after short-term treatment (7-19 days) with GRN163, average tumor size was significantly reduced in the treated versus control mice, and the survival of treated mice was significantly increased (p less than 0.01). In some cases, tumor growth in the treated mice was essentially blocked and in one case, the tumor completely disappeared.

GRN163 was also tested in an intracranial model of human glioblastoma in athymic rats. In these studies, GRN163 was tested without the lipid carrier, as it was first established that GRN163 alone could penetrate brain cells and would widely distribute itself within the hemisphere of the brain into which it was injected. In the distribution study, GRN163 was labeled with a fluorescent tag, infused by pump into the rat brain over a period of seven days and found to persist without diminution for at least four days after infusion (the longest time-point studied).

Two types of efficacy studies were then conducted in rats. In the first study, designed to mimic a model of minimal residual disease or tumor prevention, human glioblastoma tumor cells were injected into the rat brain, and beginning 1-2 hours thereafter, GRN163 was infused into the same site over a 7- or 14-day period. Five out of seven rats treated with GRN163 showed no neurological signs of tumor progression and were found to have no evidence of brain tumors at the end of the study (day 103). They were considered cured. In contrast, all four control rats required euthanasia between days 41 and 43, and were found to have large brain tumors at the site of cell injection.

In the second intracranial (within the brain) rat model, designed to mimic a typical therapeutic efficacy study, tumors were implanted into 20 rats and allowed to become established for 14 days before GRN163 or a control oligonucleotide was infused over a 7-day period into the implantation site. The control animals had a median survival of 37.5 days (range 37-43), while the low- and high-dose GRN163 animals had median survivals of 45 and 54 days, respectively, with two of the eight animals (25%) in each of the GRN163 groups being cured -- i.e., they showed no signs of a tumor and no signs of any neurological symptoms at day 94 when they were sacrificed. The increased survival of GRN163-treated animals over the control group was statistically significant at both doses.

"These rodent studies suggest that GRN163 might prove effective for the treatment of human brain tumors, as well as the prevention of relapse following surgical removal of tumors," stated Dennis Deen, Ph.D., senior author of the paper and Professor of Neurological Surgery in the Brain Cancer Research Center at UCSF.

"We believe that GRN163 or our improved second-generation compound, GRN163L, will be useful in the treatment of brain cancer," stated Calvin Harley, Ph.D., Geron's chief scientific officer. "We are currently focused on the development of GRN163L, our lipid-conjugated analog of GRN163, for the systemic (whole body) treatment of hematologic tumors in order to establish safety and pharmacological activity. However, we are optimistic that we can move into multiple solid tumor trials, including brain cancer, after demonstrating positive clinical results with hematologic tumors."

Geron has broad proprietary rights covering GRN163, GRN163L and the platform technologies underpinning this approach to treating cancer through telomerase inhibition. For example, Geron holds issued U.S. and overseas patents to the sequence of the hTR molecule and oligonucleotides derived from hTR, including GRN163 and GRN163L, and the uses of such oligonucleotides to inhibit telomerase. Geron also owns patents and patent applications covering oligonucleotides with phosphoramidate backbone linkages and methods of synthesizing such oligonucleotides. More broadly, Geron has over 180 issued patents worldwide on various aspects of telomere biology, telomerase and telomerase inhibition and oligonucleotide chemistry, and more than 95 pending patent applications.

Geron is a biopharmaceutical company focused on developing and commercializing therapeutic and diagnostic products for cancer based on its telomerase technology, and cell-based therapeutics using its human embryonic stem cell technology.

This news release may contain forward-looking statements made pursuant to the "safe harbor" provisions of the Private Securities Litigation Reform Act of 1995. Investors are cautioned that such forward-looking statements in this press release regarding product development and future applications of Geron's technology constitute forward-looking statements that involve risks and uncertainties, including, without limitation, risks inherent in the development and commercialization of potential products, reliance on collaborators, need for future capital, need for regulatory approvals or clearances, and the maintenance of our intellectual property rights. Actual results may differ materially from the results anticipated in these forward-looking statements. Additional information on potential factors that could affect our results and other risks and uncertainties are detailed from time to time in Geron's periodic reports, including the quarterly report on Form 10-Q for the quarter ended March 31, 2004.

Contacts

Geron Corporation
David L. Greenwood, 650-473-7765



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